Topresent a pictorial review of the varied imaging appearances of obstructive gallstone ileus, from a range of imaging modalities. Illustrate key findings the radiology trainee is required to recognise in order to facilitate timely diagnosis.

Epidemiology Gallstone ileus is an uncommon, but important, cause of small bowel obstruction accounting for approximately 1-4% of cases. It has an incidence of approximately 0.5% in known cases of gallstone disease, but mortality reaches up to 20%. Reaching a timely diagnosis is, therefore, essential. A diagnosis of gallstone ileus is more prevalent among the elderly. The majority of patients are also female, with figures ranging from 72% to 90%. Pathophysiology An initial episode of acute cholecystitis often precedes the diagnosis. This inflammation gives rise...

Please see accompanying figures for imaging and case study descriptions. Review of previous imaging by the radiologist is crucial to determine any evidence of pre-existing gallstone disease. Plain Film Historically described with plain film radiography, the Rigler triad is a classic appearance – small bowel obstruction, gas within the biliary tree and a visible ectopic gallstone. Direct visualisation of the calculus may not always be possible, since only approximately 12.5% are calcified. It is, therefore, of utmost importance to be familiar with additional secondary signs....

Gallstone ileus, while being an uncommon cause of bowel obstruction, is a critical diagnosis due to its high mortality and requirement of surgical management. Clinical presentation is often non-specific, and imaging is the mainstay of diagnosis. Knowledge of key imaging features in multiple modalities is, therefore, essential for effective patient management.

Presenter information: Dr David Garbera Registrar Clinical Radiology Mersey School of Radiology Liverpool United Kingdom [email protected]

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